Sunflower (Helianthus annuus) oil is a major edible oil worldwide. The oil component of sunflower seeds typically contributes about 80 percent of the value of a sunflower crop and is mostly used as a cooking medium. Sunflower oil is also used as salad oil, as well as in the manufacture of margarine, soap, shortening, lubricants, and as a source for biodiesel fuels. In the United States, approximately 1-2 million acres are planted in sunflowers annually, primarily in the Dakotas.
Objectives in sunflower breeding include improved seed yield, earlier maturity, shorter plant height, uniformity of plant type, and disease and insect resistance. High oil percentage is desirable when breeding oilseed sunflower types, whereas large seed size, a high kernel-to-hull ratio, and uniformity in seed size, shape, and color are valued in breeding and selection of nonoilseed sunflower. Other characteristics such as improved oil quality, protein percentage and protein quality are also valued.
Sunflower (Helianthus annuus L.), can be bred by both self-pollination and cross-pollination techniques. The sunflower head (inflorescence) usually is composed of about 1,000 to 2,000 individual disk flowers joined to a common base (receptacle). The flowers around the circumference are ligulate ray flowers with neither stamens nor pistil. The remaining flowers are hermaphroditic and protandrous disk flowers. The sunflower seed, botanically referred to as an “achene,” is composed of the pericarp and embryo
Natural pollination of sunflower occurs with the appearance of a tube partly exerted from the sympetalous corolla. The tube is formed by the five syngenesious anthers, and pollen is released on the inner surface of the tube. The style lengthens rapidly and forces the stigma through the tube. The two lobes of the stigma open outward and are receptive to pollen but out of reach of their own pollen initially. Although this largely prevents self-pollination of individual flowers, flowers are exposed to pollen from other flowers on the same head by insects, wind, and gravity. Both cross-pollination and self-pollination may occur naturally.